Golden algae is not native to the region and was likely introduced by someone emptying boat wells filled with water from an infected lake into Possum Kingdom Lake and Lake Whitney, TPWD biologist Melissa Tidmore said.

“Golden algae release a toxin that affects the fish’s gills,” she said. “It causes their cells to burst, and they can’t absorb oxygen.”

The bloom typically peaks in January but isn’t as noticeable because the cold weather keeps the dead and dying fish from floating. Because the bloom peaked in warmer April, dead and dying fish can be seen in areas around Possum Kingdom Lake from the south boat ramps to the dam.

According to estimates, 50,000 fish have died in Possum Kingdom Lake in Palo Pinto County. Lake Whitney in Hill County has seen more than 68,000 deaths.

TPWD said 85 percent of the fish are gizzard chad, which are usually used as bait fish. Fifteen percent of the fish that have been found dead are game fish such as bass and bream.

While it is still safe to eat fish caught in lakes affected by golden algae, experts don’t recommend consuming fish that area already dead or look like they’re dying.

The state has partnered with international and U.S. partners to research golden algae. They’ve spent nearly $4 million researching the problem, including how to manage it on a large scale.

Teams will continue to monitor fish populations in the lakes and replenish the population through the spring and summer as needed.